Disconnect the battery.
Remove the horn push.
Undo the nut holding the steering wheel in place (please invest in a proper socket or box spanner)
Remove the steering wheel.
Remove three screws that hold the switch cover in place and rmeove the cover.

You can now see the switch mechanism and a little adjustable protrusion on the steering column. The switch needs to be positioned so that the protrusion on the column hits the little levers that flick the switch to off. In extreme cases, the protrusion can be adjusted by releasing the loick nut and unscrewing a little, but that is not usually required.

When all is working correclty, reassemble as reverse of above. Note that for the cover to fit and llow the switch arm to move in the slot, the outer steering column must be correctly positioned.

Typically people release the column clamp below the dashboad and then the switch moves and does not engage with the little blimp.

For the record you'll find a permanent list of "Spanner Sizes " listed under the "Mechanical " section of the Forum ,Second Topic down. Most of the components are there.
It lists Steering wheel nut as 3/4 " Whitworth. Other sizes mentioned by posters on the site have used Metric 33/34mm sockets. So it really depends what you can get hold of / borrow.Have you got any self employed Mechanics , working from home or a van , near you that you could beg a favour from ?
If you add your nearest Town to your post details ( never your full address ) somebody in the Club might loan you one.

One further thought: Sometimes the column will have been removed from the steering rack, and when refitted, the inner column is in the wrong place. The knob/trigger/protrusion should be in approximately the 2 o'clock position when the front wheels are pointing straight ahead. That needs to be correct before making the other adjustments to ensure that the switch is in the correct position,

Years ago I had a similar problem. The indicators cancelled to the left but not to the right. The garage said that the 'cancelling oops I typed a naughty word' had worn down over the years. They sorted it out with a dab of plastic metal or something. It's been fine ever since.

ok
i have had the steering wheel off and i can see the oops I typed a naughty word isnt hitting anything
does it have to hit very small triangular pieces of metal that have a small delicate spring attached ?

That looks to be in order. Here's a working switch in the centre or off position:

Centred.JPG (65.67 KiB) Viewed 259 times

Now with the left hanbd position on, we can see one of the triggers sticking out furter:

Left.JPG (79.19 KiB) Viewed 259 times

Because the trigger is spring loaded, the itt (it will forever be that on this board) can pass from the centre outwards without any problem, but as it returns to the centre, it will hit the trigger and cancel the indicator.

The same applies when the right turn is in play:

Right.JPG (46.05 KiB) Viewed 259 times

If the itt is hitting the trigger then it should self cancel. With everyhting lined up correctly, the only adjustment would be ot extend the itt a little; and if that doesn't work then you're probably looking at a new switch. The connections are bullet style and can be accessed by removing the glove box liner.